3-D printing has changed the way that engineers and designers prototype things, but it hasn’t really made its way into mainstream manufacturing yet. But engineers at EADS, the European Aeronautic Defence and Space Company, are making strides by using a process called additive layer manufacturing, which uses a laser to melt plastic, nylon or metal powders in layers until the finished product is “printed.” EADS used the technique to print a fully functional bike out of nylon, which the company says is as strong as steel.